JP4079534B2 - Measuring head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a measurement head that detects contact with a measurement object used in a coordinate measuring machine, a machine tool, or the like, or displacement due to contact, and particularly relates to a measurement head provided with means for suppressing vibration of a feeler during measurement. .
[0002]
[Prior art]
A measurement head for measuring a displacement with or after contact with a measurement object includes a hollow housing and a feeler for contacting the measurement object. The feeler is formed of a long member, and is fixed to a support member (support plate) provided in the housing at one end thereof. The support plate is movably supported by a spring or the like in the housing. Further, a detector for detecting the displacement of the support plate is disposed in the housing. In this type of measuring head, when the feeler contacts the object to be measured at its tip, the tip of the feeler is displaced, and the displacement appears as the displacement of the support plate, and the moment of contact is detected by the detector. is there. Examples of the detector include a touch type using a micro switch that detects contact with an object to be measured, and a displacement measurement type using a differential transformer that detects displacement of the feeler.
[0003]
Such a measuring head is used in a measuring machine that measures a two-dimensional shape or a three-dimensional shape. It is also possible to attach this measuring head to the spindle of the machine tool. In this case, the position coordinates of the X, Y, and Z axes of the machine tool when contacting the measurement object are read through the NC device of the machine tool, and the dimensions of the measurement object, for example, the processed workpiece Measure the dimensions. In this case, for example, the measured dimension is used to rework the insufficiently machined part of the workpiece.
[0004]
[Problems to be solved by the invention]
When a penetrating force is applied by acceleration and stop when positioning or approaching operation is performed, vibration is generated in the measuring head, particularly the feeler. The amplitude of the vibration is erroneously detected as a contact or displacement by the detector of the measurement head, and there is a problem that a measurement error occurs or measurement reproducibility deteriorates. In order to avoid this problem, in the prior art, the feed speed is reduced to such an extent that vibration does not occur in the measuring head.
[0005]
An object of the present invention is to provide a measurement head that suppresses and attenuates vibration generated in the measurement head during a measurement operation, thereby enabling highly accurate measurement.
[0006]
[Means for Solving the Problems]
The present invention solves this problem by providing a buffer means for suppressing and attenuating vibration during the measurement operation in the housing of the measurement head.
That is, the present invention provides a measurement head including a housing and a measurement feeler supported by the housing and in contact with an object to be measured, and a support member provided in the housing and fixing a base end portion of the measurement feeler. A first damping unit disposed on the feeler side with respect to the support member; and a second damping unit disposed on the opposite side of the feeler with respect to the support member, for supporting the support member. The measuring head is characterized in that the supporting member is supported by the first damping means and the second damping means .
[0007]
[Action]
In the first aspect of the present invention, the support member is supported from both sides by the vibration damping means, and vibration energy of the support member is converted into heat and dissipated .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment related to the present invention will be described with reference to FIG.
The measurement head 11 according to the first embodiment includes a hollow housing 9 and a feeler 7 for contacting the measurement object. The feeler 7 is formed of a long member, and is supported by the housing 9 so as to be swingable so that the tip 7a can touch around the central axis O. More specifically, the feeler 7 has a base end 7 b attached to a support plate 5 (support member) disposed in the housing 9, and the support plate 5 protrudes from the inner surface of the housing 9. 13, a spring 17 for pressing and urging the support plate 5 toward the fulcrum 13, and a dashpot 15 as a buffer means arranged in parallel with respect to the spring 17. The spring 17 and the dashpot 15 act as vibration suppressing means for suppressing and absorbing the vibration of the feeler 7. Further, a micro switch 19 for detecting the displacement of the support plate 5 is disposed in the housing 9. The microswitch 19 detects the displacement of the support plate 5 and generates a detection signal. Although two fulcrums 13 are shown in FIG. 1, the support plate 5 is actually supported at three points by the three fulcrums 13.
[0010]
The measuring head 11 is attached to, for example, a spindle of a machine tool (not shown), and three of X, Y, and Z are measured with respect to an object to be measured such as a workpiece (not shown) by a machine tool (not shown). By relatively sending in the axial direction, it can be used to measure the dimensions of each part of the workpiece. At that time, when the feeler 7 comes into contact with the measurement object at the tip 7 a, the tip 7 a of the feeler 7 is displaced, and the displacement appears as the displacement of the support plate 5. Then, the shape of the workpiece can be measured by reading the position coordinates of the X, Y, and Z axes when the detection signal is generated from the micro switch 19 with, for example, an NC device of a machine tool.
[0011]
The feeler 7 vibrates when the measurement head 11 is given relative feed in the X, Y, and Z directions and when the feeler 7 of the measurement head 11 comes into contact with the measurement object. In the conventional measuring head, it takes time to converge the vibration of the feeler, which causes a measurement error and decreases the reproducibility of position measurement. According to the present embodiment, since the spring 17 and the dashpot 15 as vibration damping means suppress and attenuate the vibration of the feeler 7, the above-mentioned problems of the prior art are solved.
[0012]
Next, a second embodiment related to the present invention will be described with reference to FIG.
The measurement head 21 according to the second embodiment is configured in substantially the same manner as the measurement head 11 of the first embodiment, and includes a hollow housing 9 and a feeler 7 for contacting the measurement object. The feeler 7 is supported by the housing 9 so that it can be displaced. More specifically, the support plate 5 to which the base end portion 7 b of the feeler 7 is attached includes a fulcrum 13 protruding from the inner surface of the housing 9, a spring 27 and a spring for pressing and urging the support plate 5 toward the fulcrum 13. 27 is supported by a dashpot 25 arranged in parallel. A micro switch 29 is attached to the support plate 5. Although two fulcrums 23 are shown in FIG. 2, the support plate 5 is practically the same as that of the first embodiment in that it is supported at three points by the three fulcrums 23.
[0013]
In the first embodiment, the fulcrum 13 is disposed on the opposite side of the feeler 7 with respect to the support plate 5 in the housing 9 (see FIG. 1). In the second embodiment, the fulcrum 23 is located in the housing 9. A spring 27 as a damping means and a dash pot 25 arranged in parallel to the support plate 5 are arranged on the opposite side of the feeler 7 with respect to the support plate 5. Yes. Also in the second embodiment, the point that the spring 27 and the dashpot 25 as the vibration damping means suppress and attenuate the vibration of the feeler 7 is the same as in the first embodiment.
[0014]
Next, a third embodiment of the present invention will be described with reference to FIG.
The measurement head 31 according to the third embodiment includes a hollow housing 9 and a feeler 7 for contacting the measurement object, like the measurement heads 11 and 21 of the first and second embodiments. The feeler 7 is swingably supported by the housing 9, but in the third embodiment, unlike the first and second embodiments, the housing 9 has a fulcrum for supporting the support plate 5. Not arranged. The support plate 5 includes a first spring 37a serving as a first damping unit disposed on the feeler 7 side with respect to the support plate 5, a first dash pot 35a disposed in parallel to the first spring 37a, and the support plate 5. Is supported by a second spring 37b as a second damping means disposed on the opposite side of the feeler 7 and a second dash pot 35b disposed in parallel with respect to the second spring 37b. . A micro switch 39 is attached to the support plate 5. Also in the third embodiment, the first spring 37a and the first dash pot 35a as the first vibration damping means, and the second spring 37b and the second dash pot as the second vibration damping means. The point that 35b suppresses and attenuates the vibration of the feeler 7 is the same as in the first and second embodiments.
[0015]
In the above-described embodiment, the vibration damping means is disposed substantially parallel to the center axis O of the feeler 7, but the present invention is not limited to this, and may be provided in the vertical direction with respect to the axis O.
[0016]
Next, a fourth embodiment related to the present invention will be described with reference to FIG.
The measurement head 41 according to the fourth embodiment includes a hollow housing 9 and a feeler 7 for contacting a measurement object, like the measurement heads 11, 21, and 31 of the above-described embodiments. 7 is supported by the housing 9 so as to be swingable. The support plate 5 that fixes the base end portion 7 b of the feeler 7 is supported by a fulcrum 43 protruding from the inner surface of the housing 5 and a spring 47 for pressing and urging the support plate 5 toward the fulcrum 43. In the fourth embodiment, unlike the embodiment described above, no dashpot is provided, and instead, the support plate 5 and the fulcrum 43 are covered with an elastic rubber 45 as a buffer member. . A micro switch 49 is attached to the support plate 5.
[0017]
As described above, when the feeler 7 vibrates during measurement, the vibration is transmitted to the support plate 5. In the present embodiment, this vibration is suppressed and damped by the spring 47 and the elastic rubber 45 as damping means. Needless to say, vibration can be damped by the internal damping of the elastic rubber 45, but the buffer member may be formed of a vibration-absorbing resin that performs the same function instead of the elastic rubber 45. In FIG. 4, the fulcrum 43 is disposed on the inner surface of the housing 9 so as to contact the surface on the feeler side of the support plate 5, but is provided so as to contact the opposite surface as shown in FIG. 2. May be. Further, in FIG. 4, the fulcrum 43 and the entire support plate 5 are covered with the elastic rubber 45, but the elastic rubber 45 is arranged so as to connect at least the contact point between the fulcrum 43 and the support plate 5. Just set up.
Instead of using a dashpot, rubber, or resin as the buffering means, other means having damping ability may be used.
Further, the contraction allowance of the springs 17, 27, 37 a, 37 b, 47 can be changed with screws or the like, and the vibration absorption can be changed by changing the support force of the support plate 5. Alternatively, the spring constants of the springs 17, 27, 37a, 37b, 47 can be changed using spring constant changing means, and the vibration absorption can be changed by changing the support force of the support plate 5.
[0018]
Next, a fifth embodiment related to the present invention will be described with reference to FIG.
The measurement head 51 according to the fifth embodiment includes a hollow housing 9 and a feeler 7 for contacting the measurement object, like the measurement heads 11, 21, 31, 41 of the above-described embodiments. The feeler 7 is supported by the housing 9 in a swingable manner. The support plate 5 to which the base end portion 7 b of the feeler 7 is attached is supported by a fulcrum 53 protruding from the inner surface of the housing 5 and a spring 57 for pressing and urging the support plate 5 toward the fulcrum 53. In the fifth embodiment, as in the fourth embodiment, no dashpot is provided, and instead, a vibration sensor 59 and a vibration exciter 55 are attached to the support plate 5. Similar to the embodiment described above, the microswitch 61 is attached to the support plate 5.
[0019]
When the feeler 7 vibrates during measurement, the vibration is transmitted to the support plate 5. In this embodiment, this vibration is sensed by the vibration sensor 59, and its frequency and amplitude are detected. Based on the frequency and amplitude detected by the vibration sensor 59, vibration that cancels the vibration detected by the vibration sensor 59 by a vibration control device (not shown) including a separately provided microprocessor and vibration driver circuit. Is generated by the vibrator 55. Thereby, it becomes possible to suppress and attenuate the vibration of the feeler 7.
[0020]
【The invention's effect】
According to the present invention, the damping means including the spring that presses the support member to which the base end portion of the feeler is fixed to the fulcrum and the buffer member provided between the support member and the housing suppresses vibration of the feeler. Therefore, the measurement accuracy and reproducibility of the measurement head can be improved. Furthermore, according to the present invention, the vibration control means suppresses and attenuates the vibration of the feeler while the measurement head is approaching or moving away from the measurement object, so that the measurement head can be moved at high speed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a measuring head according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a measuring head according to a second embodiment of the present invention.
FIG. 3 is a longitudinal sectional view of a measuring head according to a third embodiment of the present invention.
FIG. 4 is a longitudinal sectional view of a measuring head according to a fourth embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of a measuring head according to a fifth embodiment of the present invention.
[Explanation of symbols]
5 ... support plate 9 ... housing 7 ... feeler 11 ... measuring head 13 ... fulcrum 15 ... dashpot 17 ... spring

Claims (2)

In a measurement head comprising a housing and a measurement feeler supported by the housing and in contact with an object to be measured,
A support member provided in the housing and fixing a base end portion of the measurement feeler;
First damping means disposed on the feeler side with respect to the support member;
Second damping means disposed on the opposite side of the feeler with respect to the support member;
And a fulcrum for supporting the support member is not provided, and the support member is supported by the first vibration suppression unit and the second vibration suppression unit. Measuring head. The first vibration damping means includes a first spring disposed substantially parallel to the center axis of the feeler, and a first dashpot disposed in parallel to the first spring,
The second damping means includes a second spring disposed substantially parallel to the center axis of the feeler, and a second dashpot disposed in parallel to the second spring. Item 2. The measuring head according to Item 1.

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